Einstein’s Riddle (The Zebra Puzzle)
January 11th, 2009
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This is my 200th post. Thus, I can now say I’ve written hundreds of posts, instead of dozens. It will take 1,800 more posts before I can say I’ve written thousands, so this is a nice milestone!
I heard about this puzzle from @marelisa on Twitter, and I found a related but harder version on Wikipedia. It’s known as either Einstein’s Riddle, or The Zebra Puzzle. Albert Einstein allegedly created it as a boy, and he said that only 2% of the world’s population could solve it.
While it’s not clear whether it was actually created by Einstein, the 2% figure seems about right, especially because most people haven’t tried a puzzle like this before. But if you’re feeling up to it, I’ll give both versions of the puzzle, followed by some tips on how to do it.
Here’s the version of Einstein’s Riddle that Marelisa found. (Note there’s no zebra in this one.)
- In a street there are five houses, painted five different colors.
- In each house lives a person of different nationality.
- These five homeowners each drink a different kind of beverage, smoke a different brand of cigar, and keep a different pet.
Einstein’s riddle is: Who owns the fish?
Necessary clues:
1. The British man lives in a red house.
2. The Swedish man keeps dogs as pets.
3. The Danish man drinks tea.
4. The Green house is next to, and on the left of the White house.
5. The owner of the Green house drinks coffee.
6. The person who smokes Pall Mall rears birds.
7. The owner of the Yellow house smokes Dunhill.
8. The man living in the center house drinks milk.
9. The Norwegian lives in the first house.
10. The man who smokes Blends lives next to the one who keeps cats.
11. The man who keeps horses lives next to the man who smokes Dunhill.
12. The man who smokes Blue Master drinks beer.
13. The German smokes Prince.
14. The Norwegian lives next to the blue house.
15. The Blends smoker lives next to the one who drinks water.
Here’s the version of The Zebra Puzzle in Wikipedia. This is the first known publication of the puzzle, from 1962. While similar to the version above, it’s significantly harder. As far as I can tell, it requires making a guess from multiple possibilities, then looking ahead to see how it pans out, and backtracking if it doesn’t work.
1. There are five houses.
2. The Englishman lives in the red house.
3. The Spaniard owns the dog.
4. Coffee is drunk in the green house.
5. The Ukrainian drinks tea.
6. The green house is immediately to the right of the ivory house.
7. The Old Gold smoker owns snails.
8. Kools are smoked in the yellow house.
9. Milk is drunk in the middle house.
10. The Norwegian lives in the first house.
11. The man who smokes Chesterfields lives in a house next to the man with the fox.
12. Kools are smoked in a house next to the house where the horse is kept.
13. The Lucky Strike smoker drinks orange juice.
14. The Japanese smokes Parliaments.
15. The Norwegian lives next to the blue house.
Now, who drinks water? Who owns the zebra?
(In the interest of clarity, it must be added that the five houses are in a row, each is painted a different color, and their inhabitants are of different nationalities, own different pets, drink different beverages, and smoke different brands of cigarettes.)
Here are some tips.
I can’t imagine solving these puzzles without using a chart to keep track of what you know. Most people would use a chart like the following, where it starts off blank and you fill in the words as you learn what’s in each house.
This is how the chart would look near the very beginning, after applying the clue that milk is drunk in the middle house.
| House | 1st | 2nd | 3rd | 4th | 5th |
| Nationality | |||||
| Color | |||||
| Drink | Milk | ||||
| Cigar | |||||
| Pet |
But this is what I did. I started with a chart listing all the possibilities. For example, each of the drink cells started off with “Water Tea Orange Milk Coffee,” which I abbreviated here as “WTOMC” so it fits. Then I began deleting options that were impossible.
Below you can see how it looks after learning that milk is drunk in the middle house.
| House | 1st | 2nd | 3rd | 4th | 5th |
| Nationality | NUESJ | NUESJ | NUESJ | NUESJ | NUESJ |
| Color | YBRIG | YBRIG | YBRIG | YBRIG | YBRIG |
| Drink | WTOC | WTOC | M | WTOC | WTOC |
| Cigar | KCLPO | KCLPO | KCLPO | KCLPO | KCLPO |
| Pet | FZHDS | FZHDS | FZHDS | FZHDS | FZHDS |
This way is more cumbersome, and I would only do it on a computer, not on paper. But I think it makes it easier to keep track of what you know, and therefore easier to solve the puzzle. That’s because you can track every possibility you rule out, instead of only writing something down after you’ve ruled out all other possibilities.
One more tip: cross out clues after you no longer need them. As the list of clues shrinks, you fill in the details, and eventually find out who owns the fish or the zebra.
January 11th, 2009 at 5:34 am
I am going to say the German.
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January 11th, 2009 at 11:05 am
Oh man, here I thought I would have a nice relaxing Sunday and just hang out with the family and maybe work a little in the afternoon. Nothing but good cheesecake could distract me from this puzzle, and I have no good cheesecake.
Ryan
Ryan´s last blog post..New Years Reso-What Now?
January 11th, 2009 at 1:15 pm
Ok, I got it. I also came up with the German. on the first puzzle, I’m not touching the other, not today.
Thanks for the fun!
Ryan
Ryan´s last blog post..New Years Reso-What Now?
January 11th, 2009 at 11:38 pm
I’ve done the first riddle in the past, so I figured I’d ignore my husband and the kids for a few hours to figure out the second one…
It’s 11:35pm now and I think I just figured it out: the Norwegian drinks water and the Japanese has the zebra…
WOW!! My brain hasn’t worked this hard in a long time. Thanx for the mental exercise…!
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January 12th, 2009 at 12:49 am
Hi Hunter,
Wow, am I glad I saw this in my reader and didnt come here first before I solved it. People keep giving the answers! haha.
Anyhow, I skipped to the second one since you said it was harder and solved it in about an hour. The riddle is hard but solvable if you dont give up. I guess 98% of people just give up before they solve it!
Cheers,
Jeremy
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January 12th, 2009 at 6:09 pm
One of the nice things about these puzzles is that knowing the answer in advance doesn’t ruin them.
For the first one, if you arrive at an answer, it’s the right answer. It would be pretty hard to arrive at an incorrect answer. But yes, it’s the German.
For the second one, you could easily get the wrong answer if you don’t check all the clues after making a guess. Cristina was right, but you can check the full answer on the Wikipedia page to make sure you got all the other parts right too.
January 12th, 2009 at 11:40 pm
Hi Hunter: I liked the Einstein riddle too
I didn’t realize there was a similar one with a zebra. I think it’s more about arranging the clues in a systematic fashion that keeps them all in order than anything else.
January 13th, 2009 at 10:22 pm
@ Marelisa, there’s also a different version for kids, where they use snacks instead of cigarettes!
March 5th, 2009 at 2:34 am
the Dane owns the fish on Einstein’s riddle
March 5th, 2009 at 8:56 pm
@ Divine, sorry, it’s the German. If you follow the link to the riddle, it shows one way to do it.
March 12th, 2009 at 4:37 pm
I solved the zebra puzzle in about two hours.
here’s the catch; i didn’t use anything but two pieces of paper and i’m only fifteen years old. what do you think of that? ;P
March 12th, 2009 at 8:27 pm
@ Alex, congrats! But are you sure you didn’t use a pen or pencil too?
April 8th, 2009 at 3:54 am
da clues about da norwegian are contrasting.
it says da norwegian lives at the 1st house but its NEXT TO da blue house.
da only way dat can satisfy these clues is u shud list da norwegian in da 1st 2 da Last row 2 be able 2 satisfy dat dis norwegian man lives next to the blue house__by doing so, this riddle cant be solve.
but we can change one of its clues,
THE MAN WHO LIVES IN THE BLUE HOUSE LIVES NEXT TO THE NORWEGIAN.
..Please Hunter, i would love 2 know u’r explanations.
pls email me at
schatz_october@yahoo.com.ph
April 8th, 2009 at 10:12 pm
@ Jay, I’m not sure what you’re saying, but you can find the answer by clicking the “Einstein’s Riddle” link.
August 13th, 2009 at 9:52 am
Hi everyone.This is Koushik Vikram from India.I’m new to this site.The zebra puzzle was posted in another website and its really a very interesting puzzle to solve.I solved it in just an hour.I’m 17 years old.Do u think I’m special?Cuz in the other website it was mentioned that only 2% of the people in the world could solve it.Is it real?
August 14th, 2009 at 6:25 am
@ Koushik, I think the 2% statistic might be about right. Not that the puzzle is all that hard for a logical mind, but how many people are willing to try? Also, people who have done a similar puzzle before have a big advantage.
September 15th, 2009 at 12:28 pm
Yay, i did it! …….I’m only 15 XD XD
March 11th, 2010 at 9:24 pm
only took me 25 minutes
April 25th, 2010 at 8:24 am
This was so easy!
It didnt even require guessing
It is just like a simple sudoku puzzle, with words instead of numbers.
It is even easier because it only used columns, and rows next to each other.
April 25th, 2010 at 8:26 am
I am 14 and solved this in less than 15 minutes.
Go color first it is easiest, then you just have to use the possible combinations, and you will have the rest.